The invention relates generally to electronic power switches and more particularly to a method of estimating main load current circulating through a high power switch taking place at the driver unit of the switch without any need for mounting dedicated large scale current sensors in the system employing the electronic power switch, to determine the conditional state of the power switch or to estimate temperatures associated with the power switch.
Current flows through various elements of a solid state main load current conducting power switch. Some of these elements are of parasitic or unwanted nature. Voltage drops are induced in these elements during current transients.
In low voltage applications, various types of shunt devices have been employed in series to the main current path. Such use of shunt devices is not possible in high current modules because they destroy the smooth symmetry conditions and are a likely cause of overvoltage failures.
In view of the foregoing, there is a need for a technique for estimating a main load current circulating through a high power switch taking place at the driver unit of the switch without any need for mounting dedicated large scale current sensors in the system employing the electronic power switch, to determine the health state of the power switch or to estimate temperatures associated with the power switch. It would be advantageous if the technique allowed efficient protection of the high power switch by enabling self turn-off during deleterious operating conditions that could prove harmful to the high power switch.